1. Field of the Invention
This invention relates generally to surgical apparatus and more specifically to a needle apparatus and method for insufflating a body conduit or cavity.
2. Discussion of the Prior Art
In the past, abdominal surgery has been conducted through large open incisions which provide direct access to the interior regions of the abdomen. These open procedures have invited infection, have produced considerable trauma, and have increased recovery time for the patient.
More recently, less invasive procedures have been developed for conducting abdominal surgeries through tubular access devices commonly referred to as trocars. These procedures, which call for the placement of the trocar across the abdominal muscle which defines the abdominal wall, are commonly referred to as laparoscopic procedures. In these delicate operations, small surgical instruments and endoscopes are inserted through working channels of the trocars to perform various surgical functions within the abdominal cavity. The advantages of the less invasive laparoscopic surgeries are well known to include significantly less trauma and reduced healing times. These advantages result from the small puncture wounds associated with the trocars, as opposed to the large incisions associated with open surgery.
In spite of these advantages, laparoscopic surgeries are difficult to perform since the abdominal cavity is maintained substantially intact. Not only does this decrease visibility of the operative site, but it also provides a limited volume within which to manipulate instruments. In order to increase this volume as much as possible, the abdominal cavity is typically inflated or insufflated with carbon dioxide or other gas in order to distend the abdominal wall and increase the volume of the abdominal cavity. This insufflation takes place prior to, as well as during, the laparoscopic surgical procedure. Throughout this entire period, the insufflation gas must be introduced to the cavity in order initially to distend the abdominal wall and ultimately to replace any escaping gas.
In the past, insufflation has been accomplished using needle assemblies having a hollow cylindrical configuration. A needle having a sharpened distal tip is forced through the abdominal wall to provide access to the abdominal cavity through an insufflation channel. Once the sharpened tip is within the abdominal cavity, care must be taken to avoid puncturing internal organs. For this reason an obturator has been provided with the insufflation needle. Once the abdominal wall is penetrated by the needle, a blunt tip of the obturator moves beyond the sharpened tip of the needle to inhibit the further penetration of tissue.
In this configuration, the obturator is also provided with a hollow insufflation channel. This channel extends from the proximal end of the needle assembly through the channel of the obturator to an outlet port at the distal end of the obturator. The outlet port provides communication between the insufflation channel of the obturator and regions exterior of the obturator and needle.
Due primarily to the high costs associated with an operating room, it is of significant advantage to reduce the time during which this insufflation occurs. Often a patient will require as much as three liters of insufflation gas. With a typical insufflation flow rate of 600 milliliters per minute this volume will require five minutes to fully insufflate the cavity. Even a slight reduction in the period of insufflation could significantly reduce operational procedure time and therefore result in a significant cost savings to the hospital and patient.
As noted, it is important that the sharpened distal tip of the needle be isolated from the interior organs immediately upon penetration of the abdominal wall. To accomplish this purpose, the obturator has been biased from a proximal position wherein the sharpened tip is unprotected to facilitate penetration of the abdominal wall, to a distal position where the sharpened tip is isolated to prevent damage to the interior organs. A fast transition from the proximal position to the distal position increases the safety of the insufflation needle. Of course, the speed of this movement between positions is limited by the mass of the obturator. Where the transition has not been sufficiently rapid, momentary exposure of the sharpened tip has tended to damage interior organs.
In accordance with the present invention, these disadvantages of the prior art have been overcome by providing an insufflation needle apparatus having a significantly increased insufflation gas flow rate and an obturator with a much reduced mass. The flow rate may be increased by, for example, 20% resulting in a one-minute reduction in operational procedure time and a significant increase in cost savings for the hospital. The mass of the obturator is commensurately reduced resulting in a faster transition time between the unprotected proximal position and the protected distal position of the obturator. The faster transition time also produces an audible xe2x80x9cclickxe2x80x9d which communicates the event to the user.
In one aspect, the invention includes an insufflation apparatus with a needle having a lumen and a sharpened distal tip. An obturator disposed within the lumen of the needle has an axis which extends through a proximal section, an intermediate section containing an outlet port, and a distal section. A wall included in the proximal section defines an insufflation channel which communicates with the outlet port. This wall extends along the entire proximal section and has, in a preferred embodiment, a U-shaped, radial cross-section.
In another aspect of the invention, the insufflation apparatus includes a needle having an axis which extends between a proximal end and a distal end. A first wall defines a first lumen which extends along this axis of the needle. An obturator disposed within the first lumen of the needle has a second wall defining a second lumen. An axial portion of this second wall is removed to create a void which extends along substantially the entire length of the obturator. The needle and the obturator define an insufflation channel along the second lumen and the void of the obturator.
In a further aspect, the insufflation apparatus includes a needle having an axis extended between a proximal end and a distal end, and a first wall defining a first lumen extending along the axis of the needle. An obturator disposed within the first lumen of the needle has a second wall which defines a second lumen. First portions of the first wall of the needle and second portions of the second wall of the obturator define an insufflation channel of the apparatus. The first portions of the first wall extend along more than one-half of the length of the needle.
Another aspect of the invention is associated with a method for insufflating a body conduit or cavity. In accordance with this method a needle is provided with a first lumen extending between a proximal end and sharpened distal end. An obturator is inserted into this lumen of the needle. The obturator is provided with a wall defining an insufflation channel and forming at least a portion of a cylinder with an internal radius r1. By removing portions of this wall, the insufflation channel is provided with a cross-sectional area along the entire length of the channel which is greater than Πr12. This area will typically be less than about Π[r22-xc2xd(r32-r12)] and preferably about Π[r22-⅔(r32-r12)], where r1 is the inner radius of the obturator wall, r2 is the radius of the needle lumen, and r3 is the outer radius of the obturator wall. By removing portions of the wall defining the insufflation channel, the cross-sectional area is increased resulting in an increased insufflation rate. Removing the wall portions also reduces the mass of the obturator resulting in a decreased transition time between the proximal position and the distal position of the obturator.
Since the insufflation rate is equal to the cross-sectional area of the insufflation channel, calculated in accordance with the applicable formula set forth above, multiplied by the velocity of flow through the insufflation channel, it follows that an increase in the area is accompanied by a commensurate decrease in the insufflation time.